Battery not charging
#1
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after my flat battery problems this week had chance to look at it. getting 13.37v from the alternator, when tested the battery said it was good but only 45% charged.
But after a 25 mile run as soon as its turned off its flat again. No obvious problems with either but swapped battery under warranty for a new one. All works now but probably would with new battery.
Any ideas what the correct charging v should be as the battery guy said it should be 14.4v minimum and i'm at 13.37v?
Battery is only 18mths old so have a feeling it may not be as simple as that.
But after a 25 mile run as soon as its turned off its flat again. No obvious problems with either but swapped battery under warranty for a new one. All works now but probably would with new battery.
Any ideas what the correct charging v should be as the battery guy said it should be 14.4v minimum and i'm at 13.37v?
Battery is only 18mths old so have a feeling it may not be as simple as that.
#2
Electron Wrangler
Lifetime Rennlist
Member
Lifetime Rennlist
Member
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The battery guy has no idea - sounds like you are OK based on that reading alone (I assume at idle?) - it was likely just the battery.
14.4v might be OK for a chevvy - it would likely hurt your 928's battery... the way things are connected in a 928 doesn't allow the wiring voltage drops that typical Detroit iron has.
When the car is off idle (1.5K RPM or more) you should have ~ 13.8v if you do (or close) you are fine. Use a DMM
BTW your alternator voltage wil change with RPM, ambient & engine (alt) temperature, loading (battery charge state and equiupment in operation) so monitor at different times under different conditions.
It likely won't hit 13.8V at hot idle
Alan
14.4v might be OK for a chevvy - it would likely hurt your 928's battery... the way things are connected in a 928 doesn't allow the wiring voltage drops that typical Detroit iron has.
When the car is off idle (1.5K RPM or more) you should have ~ 13.8v if you do (or close) you are fine. Use a DMM
BTW your alternator voltage wil change with RPM, ambient & engine (alt) temperature, loading (battery charge state and equiupment in operation) so monitor at different times under different conditions.
It likely won't hit 13.8V at hot idle
Alan
Last edited by Alan; 03-24-2012 at 05:49 PM.